One method used for charging a built-in rechargeable battery in a piece of electrical equipment is a so-called noncontact power transmission method, in which electric power is transmitted from a battery charger by means of electromagnetic coupling (also referred to as dielectric coupling) by means of a coil. Further, there has been known a structure of a battery charger of this type in which power transmission is started after confirmation of whether or not a piece of electrical equipment (i.e. a load) appropriately placed on the battery charger is authorized equipment.
Documents concerning the background art of the present application include JP 2006-230032 A, JP 2006-60909 A, and JP 2689927 B.
There are cases in which a battery charger remains connected to a commercial power source even during a standby period in which a piece of electric equipment is not placed. In this case, the battery charger of noncontact power transmission type having a coil may suffer from malfunction of the operation when electromagnetic wave noise enters the battery charger via the coil. Further, malfunction of the operation is also likely to occur in the battery charger when a surge enters from the commercial power source due to lightning strike or the like. Here, although the example case of electric power transmission has been described above, similar circumstances can be identified in the case of transmission of a data signal by means of electromagnetic coupling via a coil.
The object of the present invention is to provide a noncontact transmission device for transmitting at least one of electric power and a data signal to a device to which at least one of the electric power and the data signal is to be transmitted, by means of electromagnetic coupling via a coil, which can operate in a stable manner even when disturbance such as electromagnetic waves and surges enters the noncontact transmission device.